In recent years, increasing attention has been directed to terahertz (THz) waves, which are electromagnetic waves with frequencies of around 100 GHz up to around 30 THz. Terahertz waves can be used in various forms of measurement and non-destructive testing such as imaging and spectroscopy.
Terahertz waves can be generated by many various methods, for example: thermal emitters, molecular lasers, free electron lasers, backward wave oscillators, Schottky diodes, photoconductive switches driven by sub-picosecond optical pulses and nonlinear optical sources based on wave-mixing in nonlinear crystals.
As a detector for detecting terahertz waves an item for converting terahertz waves to heat can be used, specifically, an item that converts terahertz waves to heat, and detects the energy, i.e. intensity, of the terahertz waves. These kinds of detection units include pyroelectric sensors, bolomoters, Golay cells and the like. Such a system is e.g. described in US 2013/0153765. Other commonly used detection schemes include: Schottky diodes, high electron mobility transistors, photoconductive switches driven by sub-picosecond optical pulses and electro-optic sampling.
As heat may be subject to external thermal noise influencing the measurement, an improved method and system would be advantageous, and in particular a more efficient and/or reliable system and/or method for detection of terahertz radiation would be advantageous.